Shaped charge apparatus



April 5, 1966 w. T. BELL 3,244,100

SHAPED CHARGE APPARATUS Filed June 11, 1964 2 Sheets-Sheet 1 W////am 7. .Be//

INVENTOR- /i' ald 1442.)

April 5, 1966 w. T. BELL SHAPED CHARGE APPARATUS 2 Sheets-Sheet 2 Filed June 11, 1964 INVENTOR- ATTORNEY United States Patent tion of Texas Filed June 11, 1964, Ser. No. 374,483 3 Claims. ((Zl. 10220) This invention relates to perforating methods and apparatus and, more particularly, pertains to new and improved perforating apparataus employing shaped explosive charges.

Shaped charges are widely and effectively used as perforating devices in well bore completions. Usually a shaped charge intended for such a purpose includes a block of explosive material which has a conical recess in its front face. This recess receives a liner having a suitable thickness and composition so that upon detonation of the explosive material, the explosive shock wave traveling toward the liner eventually collapses the liner and a high velocity perforating jet is formed along the axis of the recess. Because of the high velocity and energy content of the perforating jet it is capable of penetrating the wall of the casing lining the well bore, the cement sheath surrounding the casing and the earth formations therebeyond. It has been of concern recently that the perforating jet in the penetration of the casing or the forming of an entry hole also tends to extrude the material of the casing about the penetration or entry hole into the bore of the casing thereby forming a burr or projection which can be objectionable. The reason for extrusion of the metal is the high radial pressures exerted on the casing while the hole is being formed. The burr is objectionable since it interferes with the sealing action of a ball sealer which is used in fracturing operations to isolate zones.

It is, therefore, an object of the present invention to provide new and improved methods and apparatus for perforating in a well bore whereby there is no burr formed on the entry hole through the casing.

This and other objects of the invention are obtained by shaped charge apparatus arranged for proximate contact with a casing wall with portions thereof shaped to prevent the formation of a burr on the entry hole of a perforation.

The novel features of the present invention are set forth with particularity in the appended claims. The present invention both as to its organization and manner of operation, together with further objects and advantages thereof, may best be understood by reference to the following description when taken in conjunction with the accompanying drawings in which:

FIG. 1 is a longitudinal view of an expendable shaped explosive charge perforating apparatus constructed in accordance with the invention and shown disposed in a Well bore;

FIG. 2 is a longitudinal view of a carrier shaped explosive charge perforating apparatus constructed in accordance with the invention and shown disposed in a well bore;

FIGS. 3 and 4 are side and top views in detail of a portion of the apparatus illustrated in FIG. 1;

FIGS. 5 and 6 are side and top views in detail of a variation of the invention illustrated in FIGS. 3 and 4;

FIGS. 7 and 8 are side and top views in detail of a portion of views of the apparatus illustrated in FIG. 2.

In FIG. 1 of the drawings, there is illustrated a casing 10 in a well bore 11 which traverses earth formations 12. A column of cement 13 is disposed between the casing and well bore. Shaped charge apparatus 14 can be suspended in the casing in any usual manner and includes a 3,244,100 Patented Apr. 5, 1966 number of fluid-tight shaped charge capsules 18 which are attached to a rigid retrievable carrier 19 such as rods or a strip. Blasting cord 20 for detonation of the charges is connected to an electric blasting cap 21 which can be electrically ignited in the usual manner from the surface by wires and a power source (not shown).

At suitable locations positioning devices 15 are attached to the carrier 19. Positioning devices 15, for example, can be housings with portions 16 brought into contact with the casing wall by means of properly located spring biased arm members 17. The housing portions 16 are aligned relative to the capsules so as to bring the forward faces of the shaped charge capsules 18 into or nearly into contact with the wall of the casing. To do this, of course, requires the suitable positioning of arms 17 relative to the carrier 19 and capsules 18.

In FIG. 2, a retrievable, re-usable steel housing carrier 14a is illustrated wherein shaped charges 18a are disposed within the fluid-tight interior 22 of the housing. Port hole covers 23 through which a perforating jet may pass are located adjacent the forward end of each charge. Carrier 14a has permanent magnets 23:: aligned relative to the port hole covers so as to bring the port hole covers 23 into proximate contact with the wall of the casing.

It will be appreciated that the positioning devices as heretofore described can be interchanged so long as the function of bringing a portion of the shaped charge apparatus into proximate contact with the wall of the casing is achieved.

Referring to FIGS. 3 and 4 of the drawings, a shaped charge 18 of the type shown in FIG. 1 includes a hollow container 25 of generally conical form receiving in close interfitting relation an explosive charge 26 (shown in dashed line). A thin-walled cover 27 is provided for H the container to form a sealed capsule shaped charge.

The container and cover may be constructed of any fluid-tight, frangible material such as cast iron or the like. The container 25 can be attached at its sides to a pair of longitudinally extending rods 23 in a well bore. The charge 26 is formed with a hollowed out or conically shaped forward end which receives a closely fitting conical linear (not illustrated) constructed, for example, of copper with a suitable thickness. The charge 26 may be detonated in a suitable manner as by the blasting cord 20 disposed at the rear end of the explosive charge 26 and adapted to be detonated by the electric blasting cap 21 In operation, the blasting cord 20 is detonated and it, in turn, detonates the rear end of the explosive charge 26 and an explosive shock wave is generated which progressively collapses the liner and develops a perforating jet. The perforating jet, in turn, produces an entry hole 30 and penetration 31 into the earth formation as shown in dashed line in FIGS. 3 and 4.

The invention as illustrated in FIGS. 3 and 4 includes the forward surface 32 of cover 27 which has a cylindrical curvature substantially the same as the curvature of the casing so as to be placed in proximate contact with the wall of the casing by the positioning devices 15 prior to detonation. This arrangement effectively impedes and prevents the splashing of casing metal and formation of a burr during jet penetration.

In FIGS. 5 and 6, a conventional capsule 18b is illustrated and a retrievable bafiie strip 33 of metal is disposed along the forward ends of the capsule 18b and attached by tie rods 32a to the rods 23. Strip 33 has a curvature substantially the same as the curvature of the casing so as to be placed in proximate contact with the wall of the casing by positioning devices.

In FIGS. 7 and 8 which are details of apparatus shown in FIG. 2, a port hole cover 23 is arranged to have a cylindrical curvature the same as the curvature of a casing. It is, of course, necessary for the forward curved surface of the port hole cover to extend beyond the housing body so as to insure proximate contact with the casing wall.

\Vhile particular embodiments of the present invention have been shown and described, it is apparent that changes and modifications may be made Without departing from this invention in its broader aspects and, therefore, the aim in the appended claims is to cover all such changes and modifications as fall within the true spirit and scope of this invention.

What is claimed is:

1. Shaped charge apparatus for us in a cased well bore comprising: shaped charge means for developing, upon detonation, a perforating jet passing along a predetermined axis to perforate an adjacent surface of a casing; means for confining the adjacent surface of a casing to be perforated by said shaped charge means including a transverse member in front of said shaped charge means and with an outer face circumscribing said perforating axis and having a curvature in a transverse plane including said axis substantially the same as the curvature of the adjacent casing surface and a substantially straightline configuration in a longitudinal plane including said axis complementary to the adjacent casing surface; and means for maintaining said outer face of said member in complementary contact with the adjacent casing surface.

2. Shaped charge apparatus for use in a cased well bore comprising: a hollow carrier; shaped charge means in said carrier for developing, upon detonation, a perforating jet passing along a predetermined axis intersecting a wall of said carrier to perforate an adjacent surface of a casing; means for confining the adjacent surface of a casing to be perforated by said shaped charge means including a member on said carrier projecting outwardly from said carrier wall and with an outer face circumscribing said perforating axis and having a curvature in a transverse plane including said axis substantially the sarne as the curvature of the adjacent casing surface and a substantially straight-line configuration in a longitudinal plane including said axis complementary to the ad jacent casing surface; and means on said carrier for maintaining said outer face of said member in complementary contact with the adjacent casing surface.

3. Shaped charge apparatus for use in a cased well bore comprising: a hollow carrier having a plurality of lateral ports therein; a plurality of shaped charge means in said carrier for developing, upon detonation, perforating jets passing along predetermined axis respectively extending through said lateral ports to perforate surfaces of a casing adjacent thereto; means for confining the adjacent surface of a casing to be perforated by said shaped charge means including a plurality of port-closure members respectively covering said ports, each of said portclosure members projecting outwardly from said carrier and with an outer face circumscribing the perforating axis extending though that port and having a curvature in a transverse plane including that axis substantially the same as the curvature of the adjacent casing surface and a substantially straight-line configuration in a longitudinal plane including that axis complementary to the adjacent casing surface; and means on said carrier for maintaining said outer faces of said members in complementary contact with their respective adjacent casing surfaces.

References Cited by the Examiner UNITED STATES PATENTS 2,616,370 11/1952 Foster 10224 2,690,123 9/ 1954 Kanady 10220 2,749,841 6/1956 Jones 102-2l.8 2,947,252 10/1960 Lindsay 102-20 3,064,571 11/1962 True 102-218 BENJAMIN A. BORCHELT, Primary Examiner.

SAMUEL FEINBERG, Examiner.

V. R. PENDEGRASS, Assistant Examiner. 

1. SHAPED CHARGE APPARATUS FOR US IN A CASED WELL BORE COMPRISING: SHAPED CHARGE MEANS FOR DEVELOPING, UPON DETONATION, A PERFORATING JET PASSING ALONG A PREDETERMINED AXIS TO PERFORATE AN ADJACENT SURFACE OF A CASING; MEANS FOR CONFINING THE ADJACENT SURFACE OF A CASING TO BE PERFORATED BY SAID SHAPED CHARGE MEANS INCLUDING A TRANSVERSE MEMBER IN FRONT OF SAID SHAPED CHARGE MEANS AND WITH AN OUTER FACE CIRCUMSCRIBING SAID PERFORATING AXIS AND HAVING A CURVATURE IN A TRANSVERSE LANE INCLUDING SAID AXIS SUBSTANTIALLY THE SAME AS THE CURVATURE OF THE ADJACENT CASING SURFACE AND A SUBSTANTIALLY STRAIGHTLINE CONFIGURATION IN A LONGITUDINAL PLANE INCLUDING SAID AXIS COMPLEMENTARY TO THE ADJACENT CASING SURFACE; AND MEANS FOR MAINTAINING SAID OUTER FACE OF SAID MEMBER IN COMPLEMENTARY CONTACT WITH THE ADJACENT CASING SURFACE. 